INTRODUCTION L APAROSCOPIC SURGERY REQUIRES the creation of a working space in the abdominal cavity to allow the safe introduction of trocars and instruments and expose the abdominal contents. Intraperitoneal insufflation of carbon dioxide (CO 2 ) is the most common method used to elevate the abdominal wall and suppress the viscera. During prolonged, complex laparoscopic procedures, ex- posure to large volumes of insufflation gas at room tem- perature puts the patient at risk for hypothermia. 1–3 Pre- venting hypothermia during surgery is important because hypokalemia, 4 coagulationdisorders, 5 and increased oxy- gen consumption 6,7 are associated with surgical hypo- thermia. Furthermore, countering hypothermia appears to reduce the number of surgical wound infections and shorten the postoperative hospital stay. 8,9 In patients with cardiac risk factors, the perioperative maintenance of nor- mothermia was associated with a reduction in morbid car- diac events. 10 Although heating the insufflation gas has JOURNAL OF LAPAROENDOSCOPIC & ADVANCED SURGICAL TECHNIQUES Volume 12, Number 5, 2002 © Mary Ann Liebert, Inc. Impact of Temperature and Humidity of Carbon Dioxide Pneumoperitoneum on Body Temperature and Peritoneal Morphology ERIC J. HAZEBROEK, M.D., 1 MICHIEL A. SCHREVE, M.D., 1 PIM VISSER, Ph.D., 2 RON W. F. DE BRUIN, Ph.D., 1 RICHARD L. MARQUET, Ph.D., 1 and H. JAAP BONJER, M.D., Ph.D. 1 ABSTRACT Background: The insufflation of cold gas during laparoscopic surgery exposes patients to the risk for hypothermia. The objectives of this study were to investigate whether heating or humidification of insufflation gas could prevent peroperative hypothermia in a rat model, and to assess whether the peritoneum was affected by heating or humidification of the insufflation gas. Methods: Rats were exposed to insufflation with either cold, dry carbon dioxide (CO 2 ) (group I); cold, humidified CO 2 (group II); warm, dry CO 2 (group III); or warm, humidified CO 2 (group IV); another group underwent gasless laparoscopy (group V). Core temperature and intraperitoneal tem- perature were registered in all animals during 120 minutes. Specimens of the parietal peritoneum were taken directly after desufflation and 2 and 24 hours after the procedure. All specimens were analyzed with scanning electron microscopy (SEM). Results: During the 120-minute study period, core temperature and intraperitoneal temperature were significantly reduced in groups I, II, and III. In the animals that underwent warm, humidi- fied insufflation (group IV) and the gasless controls (group V), intraoperative hypothermia did not develop. At SEM, retraction and bulging of mesothelial cells and exposure of the basal lamina were seen in the four insufflation groups (groups I–IV) and also in the gasless controls (group V). Conclusion: Insufflation with cold, dry CO 2 may lower the body temperature during laparoscopic surgery. Hypothermia can be prevented by both heating and humidifying the insufflation gas. Changes of the peritoneal surface occur after CO 2 insufflation, despite heating or humidifying, and also after gasless surgery. Departments of 1 Surgery and 2 Cell Biology and Genetics, Erasmus Medical Center Rotterdam, Rotterdam, The Netherlands. 355